Use the last number plus 1

divide by 2 then use the

answer multiply by itself.

1+3+5+7

8Step 1 Use 7 + 1 =

Then use 8 ÷ 2 = 4

Step 2 use 4 x 4 = 16

16You will get the answer is

1 + 3 + 5 +…+ 11

Step 1 Use 11 + 1 = 12

Then use 12 ÷ 2 = 6

Step 2 use 6 x 6 = 36

36You will get the answer is

1) 1 + 3 + 5 +...+ 15

2) 1 + 3 + 5+...+ 21

3) 1 + 3 + 5 +...+ 19

4) 1+ 3 + 5 +...+ 25